The winter parliamentary break is usually time for MPs to get back to their electorates, do some travel and refresh ahead of the second half of the year.

But the five Super Saturday by-elections kept Malcolm Turnbull and Bill Shorten busy in four states for all of June and July.

And the policy debate didn't stop either, with battles over corporate tax cuts and the National Energy Guarantee.

Both of those policies face a make-or-break fortnight in Canberra as MPs return from their break.

The unpopular corporate tax cuts have been pushed to the second week of the parliamentary sitting.

It looks increasingly likely that the government will allow them to fail, or will cave to Senator Derryn Hinch's demands for a $500 million yearly revenue cap on the lowered tax rate.

That means the big banks would miss out - and every single day of the royal commission brings yet more evidence why the public is unhappy with them.

"At the moment I will not give a tax cut to robber banks when you see what they've done to bloody farmers around this country," Senator Hinch said.

A significant number of government MPs want the coalition to put the tax cuts to a vote and then dump the unpopular policy once it fails.

But Turnbull can't afford to fail on the NEG.

The policy will most likely pass the coalition party room, even with a couple of changes.

But if a large chunk of the coalition's back bench promises to cross the floor - including a former prime minister and his deputy - Labor faces a stark political choice.

Vote with the government and end a decade of spiralling power prices and bickering over climate action? Or vote with the rebels and hand Turnbull a crushing blow on a key policy?

"The time for the Liberal Party and National Party fighting each other and fighting between themselves is over, real people are paying real increases in electricity bills," Shorten said on Thursday.

Still, he'll have a political choice to make if Tony Abbott, Barnaby Joyce and their crew of backbenchers decide to torpedo the National Energy Guarantee.

Turnbull has spent more than a year on the guarantee, trying to kill off a damaging policy stalemate in Canberra.

So far he hasn't managed to break even in the polls - the latest ReachTel poll has the two-party preferred vote steady at 51-49 in Labor's favour, like it has been all year.

But the federal election will come down to 151 separate races, and Turnbull can win even if he's behind on the overall vote.

It will depend if he can hang onto marginal seats in Queensland and Western Australia - and perhaps pick up seats like Lindsay off Labor.

Emma Husar is quitting at the next election after an internal bullying investigation, leaving behind a seat she holds with just 1.1 per cent of the margin.

At the last election the polls in Lindsay were mainly wrong, and both Labor and the Liberals haven't picked their candidates yet.

The scandal should help the coalition, but that assumes the Liberals will pick an electable candidate, something they failed to do in the recent Braddon and Longman by-elections.

Turnbull will also face pressure over money provided to drought-stricken farmers and the decision to give a tiny foundation $444 million for the Great Barrier Reef.

The reef decision looked dodgy, and it's only looking more so as further details emerge.

There is public support for saving the reef - but not when the money is going to a small group which was handed the cash without a tender process.

And farmers are doing it tough. Turnbull can hand out money and pressure the banks to be kind, but he can't make it rain.

Winter is over for farmers, and it's heating up for Turnbull too.

Australian Associated Press